Photographic reversal process



Patented Mar. 12, 1

UN l1" S Com, New do u No z.

a one.

producing positive images by reversal.

Photographic reversal images are produced in two general ways. in eachof these the sensitive layer is exposed to light and the original latentimage is developed to a negative. The negative silver image produced inway is then re- ,inoved without destroying the sensitivity of theunexposed silver halide. 'fiiis is usually done by means of a bath ofpotassium permanganate and sulfuric acid. After removal of the negativesilver image in this way, the sensitive layer may be either exposed tolight or checally logged without exposure to light, to produce a latentimage which may then he developed in the usual way to produce a positivereversal image.

It is an object-oi the present invention to simplify this reversalprocess by provig a means for omitting one of the customary steps. Afurther object is to provide a method for producing a black and whitereversal image in a silver halide layer without removal of the negativesilver image prior to the final fimng step. Other objects will appearfrom the folio description of our invention.

'These objects are accomplished by w-r out the reversal development in acoupler developer which produces both a silver image and also a dyeimage which protects the silver image so i that it is not removed inlater -1 such as ferricyanide and hypo.

in care out our process the sensitive layer is first exposed, either toan object or under a transparency of an image, and is developed to anegative silver image in an ordinary developer, such as a customarymetal-hydroquinone developer. The layer is then thoroughly washed inwater and is exposed to the desired extent without removal of thenegative silver image. This exposure may he made either from theemulsion side or through the support in the case of a film or plate. Thelayer is then developed to the required density in a coupler developerwhich forms a positive silver image and a dye image simultaneously inthe layer. The coupler compound must be one which produces a dye ofsubstantially neutral grey density or which protects the positive silverimage in such a way that it is not removed in subsequent baths of theprocess. The layer is then fixed in a solution, such as potassiumferricyanide and hypo, which removes either the negative silver image orboth the negative and positive silver images without afiecting thepositive dye image. The positive ng baths.

arcane v nsvansm. rnooass Weslcy T. Hanson, Ira,

Rochester, N. E, asslgnors to Eastman heater, N.

FPF T Application dell-lull No.

1'1 FFICE Y., a corporation of April 6, was. 200,501

dye or dye and silver image rem duce substantial neutral grey dye imagesmay also he used.

Thefollowing eaamples, which are illustrative only, indicate developingsolutions which may he used'ior the reversal development, accord to ourinvention:

Example I Diethyl p-phenylene dla g Sodium carbonate do 30 Sodiumsubtitle". do 6 p-Benzyl phenol do 3 Sodium hydroxide do 5 ater to er" 1ltaumple H 2-amino-5-diethyl won: toluene chloride "er Sodium sulflte doSodium carbonate dot Potassium bromide do Potassium thio'cyanate ..dop-Benzyl phenol -do Sodium hydroxide do- Water to -Jiter-..

It is to be understood that we may use a of the usual p-phenylenediamine coupler developers other than those referred to above, such asdlmethyl psphenylene diamlne, or any other p-phenylene diamine developerconta a primery amino group. The developing solution may also containother well known ingredients and the proportions of the variousdeveloper oonstituents may be varied over wide ranges.

Other well known expedients of photographic reversal processes may beused in conjunction with our reversal development. For exple,

the light exposure prior to the reversal deve opment may be controlledto produce the desired density in the final image. ,If the originalex-.

posure is too great, a longer second exposure can be given and viceversa so that a constant developing time will aflord equally goodresults. The

process of controlling the second exposure in our process is somewhatdiflerent from that used in the customary reversal processes in whichthe silver is removed before the second exposure so that an over-exposedfilm has a high transmission and an unexposed film has a lowertransmission. In the present process an overexposed negative will have avery low transmission and an unexposed negative will have a hightransmission, and a suitable exposure control method must be used. Thismethod of controlling the density of the final image in a colordevelopment reversal process is described in Seymour U. 5. Patent No.1,939,231, granted December 12, 1933.

The action of p-benzyl phenol in a coupler developer is somewhatdifierent than that of the majority of coupler compounds in that itprevents the removal of the metallic silver by treatment in the usualoxidizing baths. 'Ilie final image is, therefore, a combined silver anddye image which is substantially neutral grey in color and which ishighly satisfactory for the production of black and white photographicimages. Although we do not wish to be limited to any particularexplanation of the reason for this action, we believe that the dyeformed by union of the p-benzyl phenol with the oxidation prodvuct ofp-phenylene diamine developing agent protects the metallic silver imagein some manner such as by formation of a protective coating of the dyearound the silver image, so that the oxidizing baths are not able toattack the silver. It is to be understood that numerous othermodifications and equivalents are possible in our process and that ourinvention is to be limited only by the scope of the appended claims.

, What we claim is: 1. The method of forming a photographic reversalimage having a substantially neutral grey color which comprises exposinga gelatino-silver halide layer to a light image to form a negativelatent image therein and developing said latent image to metallicsilver, exposing the layer to a uniform light source, without removingthe negative silver image from,the layer, developing the layer in adeveloping solution containing a p-phenylene diamine developing agentand a p-benzyl phenol coupler compound to form a positive image in the.layer and removing the metallic silver negative ie from the layer.

2. The method of forming a photographic reversal image having asubstantially neutral gray color which comprises exposing agelatino-silver halide layer to a light image to form a negative latentimage therein and developing said latent image to metallic silver,exposing the layer to a uniform light source, without removing thenegative silver image from the layer, developing the layer in adeveloping solution containing a p-phenylene diamine developing agentand a p-benzyl phenol coupler compound to form a positive image in thelayer ahd fixing the layer in a ferricyanide and hypo bath.

3. In the method of producing a black and white photographic image byreversal, the step which comprises developing the reversal image in acoupler developer containing a p-phenylene diamine developing agent anda p-benzyl phenol coupler compound. g

4. In. the method of producing a black and White photographic image byreversal, the steps which comprise developing a negative metallic silverimage in the layer and without removal of the metallic silver image,developing a reversal image in the layer in a coupler developercontaining a p-phenylene diamine developing agent and a p-benzyl phenolcoupler compound.

5. In the method of producing a black and white photographic image byreversal, the steps which comprise developing a metallic silver,negative image in the layer and without removal of the negative image,developing in the layer a reversal image in a coupler developercomprising a diethyl p-phenylene diamine developer and a p-benzyl phenolin substantially equal amounts.

6. In the method of producing a black and white photographic image byreversal, the steps which comprise developing a metallic silver neg-=ative in the layer and without removal of the negative image, developingin the layer a reversal image in a coupler developer comprising adiethyl

